Some evolutionists try to use vestigial organs as proof of Darwinian evolution, but I want to turn the tables on them and use so-called vestigial organs as evidence of design. The way I can do this is to show that even these supposedly useless organs have (or at least had) purpose. (Vestigial organs, by definition, once had a purpose.) If we have useful but not necessary features then that is good evidence of intentional design.
If God designed evolution and intelligently packed life with information such that it would result in beautiful designs of creatures, then you would expect there to be body parts that are helpful or meaningful but not necessary. Design by no means implies that every body part is going to be essential. We certainly find two hands to be useful, but we can live without two of them. We find two lungs to be helpful, but a person can technically live without two. We find the nose's protruding nature to be useful in the rain, but we could survive just fine if our noses did not protrude (like a certain type of monkey, actually). Fingerprints are good but not even close to being required for survival.
All of the nice but not necessary features of creatures bear testimony to the kindness of a wise God. They do not at all indicate an unguided process of evolution. In fact, a random evolutionary process should have produced little in the way of nice features and almost no perfect designs. Random evolution should never have produced such things as fingerprints. They are too functionally well-designed for what they do, and they are too well placed to be accidental. Maybe if we had developed fingerprint-like ridges on our whole arms and hands we could begin to wonder if it was just a random accident, but the placement of the fingerprints is too exact to be the product of a disorganized process of evolution.
No, all of creation is filled with very complex, almost perfect designs, and there are too many nice and somewhat useful features for it to have all happened accidentally. Evolution is way too organized, efficient, and precise to be a random process. The designs of cells and body parts are too complex to be the result of chance. Evolution is just too good to be true... unless it was designed itself.
Now, in my view of designed evolution, it is possible that there could be some useless anatomical structures in animals, but they would be either soon discarded by evolution or quickly transformed into something useful (exaptation). Naturalistic evolution can't allow for that. It needs to blindly experiment and do step-by-step incremental changes to lead to complex features. During such random tinkering, there would be many steps where the designs were useless, cumbersome, inefficient, or impractical. You cannot possibly have random evolution going directly from one good design to another good design. It is intuitively obvious that it would not be always possible for a complex design to arise by a gradual, step-by-step process where every step consisted of a useful design. Thus all of nature should be replete with inefficient designs or intermediate steps leading to complex features. Naturalistic evolutionists know this, and so they are desperate to find vestigial organs—organs that seem to be useless or remnants of bygone ages of evolution. However, such vestigial organs would be more a demonstration of a de-evolving process than an upward evolution from less efficient to more efficient. Darwinian evolution demands that vestigial organs and on-the-verge-of-becoming-very-useful organs be very commonplace. Otherwise, evolution sure does look, taste, feel, sound, and smell like an efficient process that had to have been designed by an extremely intelligent Person.
The evidence is overwhelmingly clear, in my opinion. Life as a whole shows no signs of gradual, random evolution as proposed by Darwin. It does indicate some form of evolution in animals—efficient adaptations. Again, designs in all of life are just too good to be the product of randomness. Life adapts too quickly and easily.
So, what about supposed vestigial organs in humans? The appendix. Body hair. Goosebumps. Tonsils. Male nipples. (Other examples exist.) The problem is that these features all either have purpose, or they had purpose in previous ages of humanity (Homo sapiens), or they are examples of developmental vestigial organs rather than evolutionary vestigial organs. The appendix, for instance, is helpful for preserving good bacteria in the intestines and was very helpful to early humans living in non-technological societies. Body hair, such as eyebrows, does serve various purposes, from social purposes to protection of the eyes to aiding in the ability to feel the air currents. Eyebrows, actually, are a good example of a useful but not necessary feature of humans. They speak better for design than a random process of evolution. Goosebumps are useful in expressing or experiencing emotion and in helping warm us in the cold (the muscles that cause them, to be more precise).
I could go on to explain the uses of other so-called vestigial organs, but I think you get the idea. Do some research and you'll find out that many of the things that were once considered vestigial are now known to have a purpose(s). We don't necessarily know the purpose of every single element of the human body, but we are finding more and more that everything has served or does serve some purpose or another. There is no absolutely useless feature of the body that has been well studied, as best I can tell. Research seems to always uncover a purpose for the features once considered useless. Just because modern technology and medicine may have caused some features, like wisdom teeth, to be less than helpful does not mean that they were useless features in past times. If wisdom teeth were once useful for past ages when people often lost their teeth as they aged, then no amount of medical progress can change that fact or suddenly make wisdom teeth an originally bad design. With our advanced technology and medicine comes the ability to safely remove the wisdom teeth, after all.
The more we learn, the more we see that the human body is brilliantly designed. Even many of the features we used to consider entirely pointless are now known to have a functional purpose. Even if the purpose is small, it can indicate intentional design. Like fingerprints, some features serve mundane purposes that are not readily apparent, but that does not make them bad designs. A bad design, like you would expect from randomness, would be something like a giant tonsil that obstructed our airway. Even if the tonsil was slightly useful, its hindrance would be worse than any benefit. Our modern society has virtually made the appendix useless, but it did serve a good and important purpose before the modern era of medicine. (Many diverse groups of animals have an appendix, by the way.) Personally, I would rather have the appendix than not... just in case I need to live in less sanitary conditions someday. The point is just that no human body part can be used as an example of something bizarre that you would expect from random evolution. Nothing in the body is just plain "stupid". That means it all appears to be the result of intelligent design, not chance.
My one caveat is that even designed evolution can result in some oddities and temporarily useless features. For instance, 'blind' mole rats have only somewhat functional, tiny eyes covered over by skin . Fish that have gotten stuck in dark caves continued to have eyes even when their eyes were useless. However, since evolution is efficient, often the fish lost their eyes. Perhaps someday people would lose their tonsils if they were no longer needed for many generations. We'd look back at tonsils as a momentarily useless feature that was indeed a vestigial remnant, in the same sense as the eyes of the fish in the cave. But, if the fish return to a lake exposed to the sunlight, they can sometimes regenerate their eyes when breeding with other similar fish, since most of the genetic information is retained in their genomes. So to, for us, tonsils would likely return if we returned to a life of unsanitary conditions or simple hunters. Are tonsils currently vestigial? For some people groups, perhaps. However, the tonsils would only be a good example of a body part that has become virtually useless due to environmental changes, not an example of random evolution causing new designs.
Useless body parts—if any truly exist—can only help prove random evolution if those body parts were never useful. Randomness should result in many examples of purely useless body parts that were never before useful. Vestigial organs were all once useful, and so they only demonstrate either loss of information or lack of purpose resulting from needs changing with the environment. The fact that vestigial organs are relatively uncommon is good evidence that evolution is not random but quite efficient in eliminating waste. So, random evolution has no basis in reality—most certainly not from looking at the few examples of features that seem useless that once had purpose in past ages.
Consider the fingerprint once more. Let's say that randomly some mutation started causing fingerprint-like ridges to form on the skin of an animal. If it were random, then it is extremely unlikely that those ridges would first get produced only on the hands and feet. So, they might start forming at first on the stomach. But that's quite useless. How long would it take before the right mutations came along and accidently moved the ridges to the right places (hands and feet)? Probably hundreds of thousands of years or millions of years. This means that evolution would need to tolerate a useless feature for probably millions of years before it became a mildly useful feature. Why wouldn't evolution just discard the useless ridges before they mutated to the correct placement? Random evolution would obviously need to tolerate lots of uselessness. Now, once the fingerprints got moved to the hands why wouldn't random evolution just mutate them out of existence or move them again to some other location? It would be random, right? Obviously, evolution could not be random. It would need to be finely tuned and efficient, preserving useful features and discarding useless ones with a high degree of discrimination. Survival of the fittest by itself cannot explain these slightly useful features like fingerprints, because they are not significantly helpful in survival. Fingerprints cannot magically appear when needed for survival in Darwinian evolution. It takes time—lots of time. It takes trial and error. It takes getting it completely wrong the first time. Hence, random evolution absolutely demands the toleration of useless body part designs that were never before useful but are potentially on the verge of becoming useful.
Vestigial organs are not an example of such uselessness. Even if the appendix is entirely useless today, it did have purpose and cannot be used as an example of evolution trying to come up with some new design. At best, it shows that loss of information is sometimes to the advantage of a creature. What we don't see is humans growing another set of arms or another heart, for example. Now that could be useful and relatively simple, since it does not require much new design information.
The question for Darwinian evolutionists is, “Where are the many useless body parts that are the experiments of random evolution 'trying' to discover new, good designs?” If such body parts do not exist, then Darwinism is a hopeless theory.